Improvement in taming



PATENTED MAR. 31, 1863.

H, W. ADAMS. TANNING.

rs FEYERS 00.. vnarammumusmnavon. n. c.

glnitrh glans gum: @ffirr Letters 12mm No. 76,134, dated film's]; 31, 1868.

IMPROVEMENT IN TANNING.

'itigi grinds more in. it tips: ilfilltts not: amt noting rail of tip time.

TO ALL WHOM IT MAY CONCERN:

Be it known that I', HENRI W. ADAMS, of Milton, Northuniherland county, Pennsylvania, have invented a new and improved Mode of Tanning Leather; and I hereby declare that thefollowing is a full and exact description thereof. i

To prepare the way for a clearer understanding of the real nature of my invention, it may be proper to make the following preliminary observations: Leather is an intimate combination of tannic acid with the gels, tine of the cellular tissues of theskins and liidesdof animals. lhis reaction is so distinct that one part of gelatine in like thousand parts of water is instantly detected by the infusion of galls. The Constitution oi the prccipitatovaries according aspire or other of these materials is employed in excess, the tannic acid and gelatine being-capable ofuniting in at least three different proportions. Onehnndred parts of dry gelatine cornhinc with one hundred and thirty-six .parts of tannic acid, when the letter is in great excess.- This compound contains on atoni ofcach ingredient. I

I The common process of manufacturing leather is to clean the skins and hides, by digestion with lime and scraping with a knife, from the hair and epidermis on the one side, and the loose cellular tissues on the other, and then to steep them in pits or rots containing an infusion. of hemlock or oak-bark, valonin, sumach, or other of the substances rich in tunnic acid. At first the tanning-liquor is used very Weak, as otherwise the surface of the shins and hides becomes dark-colored and impervious, and the interior cannot afterwards be properly tanned. But having passed through a succession of liquors, gradually increasing in strength, the skins and hides" are, in the lastpitor vagintretratified with hemlock, oak, or other tanning-bark, and so, for a considerable time, submitted to the actionoi' strong tannic acid, concentrated to its highest degree, until the conver' sion into leather is' complete throughout the entire substance. They are then removed and subjected to' cleaning and finishing processes which are well known to practical tanuers, and which do not need to be particularly described; The time consumed in these tedious operations is generally from four months 'to one year, and even in many instances longer, according tothe thickness of the skins and hides, sud-also to the quality of the leather to be manufactured. l I

Many experiments have been made, in divers ports of the world, and many patents granted for sundry processes of quick tanning.- These have, for the most part, proved failures when reduced to practice upon a. large scale. Most ta-nners,'prone to follow the oldmethods, believe that a. long time is necessarily required for tannic acid to penetrate the interiors of skins and hides, and combine with their gelatinous tissues, and that no expenditure of capital, industry, or skill can ever develop a process of ahbroviating tliis period with out seriously damaging the lest-her. They have heenconfirrued in this opinion by the poor quality of leather produced by most of the quick-tanningprocesses. Strong chemicals 'or heated liquors have generally formed one of thcmost clllcacious agents in eiiecting quick tanning. Both of these, however, bytheir destructive influence upon animal tissues, have invariably resulted in rendering the leuther rotten and Worthless.

In reflecting upon this very important suhj ect,'it appeared to me that if skins and hides could be thoroughly tanned, without involving additional detrimental clients, in the course of a few days, instead of as many months as the present process requires, the quality of the, leathersrould be very much improved in strength and durobility, and the aggregate of more frequentprofits'on the capital so often turned over would be very greatly augmented." It appeared rational that the longer the cellular tissues of skins and hides were sub merged in liquors containing water, gallic acid, and injurious compounds which do not precipitategelatine, and which therefore do not tan and prcserie animal tissues, but promote their weakness and decoy,-tl1e more these tissues would be undergoing destructive decomposition. Hence concluded the quicker the tannic acid could he made to penetrate and units with them, the sooncrithey'could be removed from the deleterious liquors, and the less they would, he Cloning-edthereby. Reasoning upon this principle, I became satisfied that the quick est possible method of tanning without injuring the tissues of skins and hides would inevitably produce a superior quality of 'leatherf, I v p l 7 Chemistry having been'during mcny years one of my fuvoritcstudies, I was convinced that the old theory of tanners generally, tliaba long time is n'eoossary for tannic acid to combiuewith the glutinous tissues of slcius und hides, wascontraryto the true doctrine of chemical afiinities. Both theory and observation had impressed me with the belief that these atlinities take place at insensiblodistances, that is, upon absolute contact, and that when the conditions of this aflinitizing contact are complete, instantaneous combination occurs. It was also well known to me that an increase of temperature generally, although not always, increased the energy of chemical aiiinitics. Against the use, however, of heated tanning-liquors, I was already forewarned, by witnessing their destructive effects upon leather in many quick-tanning processes.

The only practical and feasible way, therefore, in which any really scientific improvement could be made, without resort to either chemicals or heatedliquors, in shortening the time of tanning leather'without damaging its quality, seemed to me to be, to discover, if possible, if some obstacle did not interpose itself bctweenthc gelatinous tissues of skins and hides in the ordinary tanning process, and the tanning-liquor, which prevented that absolute contact of the two combining elements which a. more sudden union required; and to ascertain, also, whether or not, if'such an interposing obstacle existed, it could be practically removed. Under these circumstances I commenced a series of experiments, carefully conducted, with a view to determine these impor- I taut quest-ions. These experiments were too numerous and varied to be detailed in this specification. They alln'esulted, however, in demonstrating beyond the shadow of a doubt, that such an interposing obstacle between the gelatinous tissues of skins and hides, and the tannic acid in solution in the tanning-liquor, did exist, and

that it was the chief hindering cause of instantaneous contact and combination.

This chief obstacle to quick tanning is the exhausted water which fills the centralporcs of the skins and hides, and which, in passing through their surfaces, leaves its tannic acid in combination with the surface tissues. This is the reason why the surfaces of skins and hides are tanned first, and their centres are left still perfectly raw, and yet soaked with water, deprived of tannin, which exhausted water neither tans nor allows fresh acid to enter and occupy its place.

It becameobvious to me, from this well-ascertained obstacle to quick tanning, that the only thing necessary to be done, other things being equal, to exteinporize the process of manufacturing leather of a superior quality, and substantially, too, by the old method, with infusion of bark alone,.without the use of chemicals or heated liquors, wasto devise some simple, practical, and economical means of removing the said exhausted water from the central pores of skins and hides as fast asitaccumulates, robbed of its acid inits passage through their 'surfaces,.in order to make room forfresh arrivals of tannin to their centres, for continuous con- 7 tact and combination.

Divers methods of accomplishing this prime object occurred to my mind, very many of which I tested with much patient and tediouslabor, and the expenditure of both capital and time. Different degrees of success attended all these efforts.

In'selecting from among these mechanical devices one which is the least obnoxious to practical difficulties and objections, and-which, in ,myjudgment, is the most desirable and profitable to introduce to the public in order to realize the highest and most satisfactory results of my invention, I have had special regard to simplicity and economy of construction, convenience of operation, capacity of tanning, the least number of hands required to produce a given amount of leather, and, in general use, the most eiiicicnt and durable mechanical arrangement, to satisfy the best conditions of quick tanning and silence the cavils of time-grown prejudice.

To enable others skilled in the art of tanning to make and use'my'invention, reference is hereby made to the drawings and letters which accompany these specifications.

A represents the model of. a tan-yard, with three tan-vats, B O D, with three revolving tanners, E F G, rotating in them. Only three are shown in the drawings, because its limited size precludes the representation of a longer series; but in practice, upon a large working scalc,'it is designed to continue this series to fif een or twenty vats, more or less, with revolving tanners in each, all constructed and. communicating as represented in the drawings, and used as co-effieient tanncrs of E, through which series skins and hides are advanced, from a raw state, through the various stages of tanning, in increasing strength of liquors, until they are finished in E. i v

v The letters Q and R represent the partitions between the rats 13 D. The letter S indicates an inlet pipe, through which concentrated tanning-liquor is supplied to the vat B; from thence itflows,weakened by th'e amount of tannin abstracted from it by the skins and hides in the revolving tanner E, into the'vat 0, through a hole in the partition Q, near the bottom; and from' thence, weakened again by the skins and hides-in the revolving tanner F, it flows through a hole in the partitipn It, near its bottom Iedgc, into thevat D; an'dso through any number of communicating vats,.it passes on until it finally flows out of the last vat in the series,

the most reduced in strength, through a hole-represented in the vat D by the letter T. In this mannerithe entire series of valts is supplied with a. constant flow of tannin'g-liquor, decreasing in strength in each vat of'the descending series from the most concentrated acid and finishing-vat B, to the weakest acid and raw-hide vat at v the opposite end of the series.

The revolving tanners E F G, being peculiar in construction and operation, require a more particular description. In a working tan-yard of some considerable size, it is deemed best to build them about six feet long, more or lessfand three or four feet in diameter. Each tanner can best determine the proper size and number of these revolving tunnels by the amount of leather he wishes, in a given time, to turn out. They are made circular for the purpose of rotation. Their heads 'or ends are attached or fastened together by barsor slats U V W, which are separated from each other. by open spaces, sufficient to allow the tanning-liquor in the vats B G D to flow freely through them, and fill a portion of the interior of the said tanners, and supply tannin to the skins and hides contained in them. Care must be taken not to separate these bars or slats so far apart as to permit the skins and .hides to fall through these open spaces when the tann crs are rotated. They must also be made of suflicicnt strength to hold the weight of skins and hides with which they are designed to be charged, and towithstand their force when tumbled about in them during the rotation of the t'anners. It

may be considered, however, that the great weightof thesetanners', when charged with skins and hides, is partially neutralized by the buoyant power of the tanning-liquor inwhich they rotate. Each of the said bars or sluts is pierced with holes an inch or'an inch and a half in diameter, more or less, and some two inches apart, more or less, into which pins, turned in a luthe,-out of hard wood, with shoulders at one end and rounded at the other, are driven, leaving the rounded ends projecting tivo inches long, more or less, into the inside of the tanncrs. ,Thc said-bars or sluts are secured, atcach end, tothe pcrimeters of the heads or ends ofthe tanners 'by belts or screws, made of brass, gun-metal, or other metal which does not form a coloring-compound with tannic'acid. The object of the said pins is to punch, pound, 'bcat,,and work the skinsand hides continually,

displacing the exhausted water from their pores, injecting fresh liquor into them, and keeping up a constant.

mot lo n of the tanning-infusion, in Contact with their gelatinous tissues, by which they are rapidly converted i rto leather.

For the purpose of charging and discharging the revolving banners, the movable bars or doors H I J are provided. The letters XYZ represent their metallic fastcnings to the ends of the runners. The lateral motion of these doors is, prevented by shoulders or steps out at each end and fitting against the inside of the said fastenings. These fastenings are firmly-secured to their places by belts or screws, which, with the fastenings themselves, should be made of brass, gun-metal, or other metal incapable of discoloring the tanningdiquoin. Other devices for securing these doors may be employed, and other materials than metal substituted.

The said revolving tunners E F G, thus substantially manufactured, are suspended and rotated on the pins K L M N O P, in journals, in the ends of the vats B C D, respcctively, in such a manner that when the said vats are filled with Eanni-ng'liquor, they are partially submerged in it. By this means the skins and hides with which they are charged are supplied with the diluted extract or infusion. of tanning-barks, or astringent salts, or other tanning-agents.

Thescrevolviug tanners may be manufactured and used singly, or combined in a series of any required number, the first three of which are represented in the'drau'ings The letter K represents a drum, to which a driving-belt is attached for the purpose of rotating the tanner, E. Another belt, or chain, or cord, connects N 0 together, and'anotber, L M. By this means all the tanners are put in motion- Various other mechanical devices may be employed to accomplish the same end.

A belt from a driving-shaft may be attached to each separate drum, K L M. Each revolving tanner in the series may be so arranged as to be thrown out of gear, at anytime, without regard-to any other one of the series. One revolving tanner may be employed to tan small stocks of leather. In such cases, the operation will be substantially as l'ollows: The skins and hides are to be freed from hair, and prcparedfor tanning in the ordinary manner. The slat or door H, in the tanner E, is removed, and the said tanner charged with skins or hides. The door is then closed. The number will vary according to the size of the tanner. Room should be left for their free tumbling over upon the projecting pins during the process of rotation. The Vat Bis next filled with thcn'eakcst lukewarm liquor employed by tanners for ratv hides. A driving-belt is attached to the drum, K, and the tanner E put in motion. "Experience will teach each practical operator what is the most desirable speed. A medium rate ofmoticn, neither too rapid nor too slow, is the best The skins or hides will be carried up, by the rotary motion of the tanner E, on its inside in the direction of its rotation, and thrown forward and over against the projecting pins in the opposite and bottom bars or slats. The tanning-liquor,

flowing through the open spaces between the bars, partially fills the tanner E, and saturates the. skins or hides.

Their continual agitation, tumbling over, and impingement upon each other, and upon the said pins and slats, softens, plumps, and thoroughly works them, opens their pores, injects the tanning-liquor into them, forces the exhausted water outof their interiors, and bringsperpetually fresh tnnningdiquor, rich in tannic acid, into continual contact with their gelatinous tissues, in their centres as well as surfaces. The revoluti'on of the tannor E in the vat 13, agitates and mixes the tanning-liquor in said vat, and keeps it uniform in specific gravity and tanning efficacy. This rotary operation goes on until the shins or hides are sufiicien-tly-plumped and ailec'ted bythe weak -acid to be prepared to receive a stronger infusion of tannin without damage to the leather. A practical tanner can easily determine this period. The time will vary according to the character of the materials operated upon. Skins, being thinner, are more quickly affected than the thicker and denser hides. But a few hours will bc sufficient in either case. I

The liquor is new drawn oil by a siphon, or other means, and the vet replenished with a stronger infusion, richer in tannic acid. I am new supposing a practical and sliilful tanner is conducting-the operation, and requires no instruction respectingtheneccssity, method, and limit of strengthening tanning-liquors during the advancing stages of converting raw shins and hides into the most superior quality of leather. The tanner. E is againput in motion, and continued in its revolutions until an examination indicates to the practised eye that the time has arrived for the substitution of a still stronger liquor. This process goes on, increasing the strength of the acid infusion, from .time to time, as the leathery combination advances, until the most concentrated liquor is finally used to convert the entire tissues into perfect leather. The charge is then removed, dried out,-

and finished in the ordinary methods.

' After being taken from the tanner E, the denser and thicker sole-leather, and perhaps some other qualities, if desired, may be laid away in common vats, i'nterstratified'with ground bark, in the usual manner, to be filled with crystalline tannin, solidified, and augmented in weight to any desired degree.

Amuch better quality of leather can be made, by this process of'quicli tanning, in from ten to thirty days, thanby the old, unscientific method which occupies nearly as many months.

Toughness and durability are the prime qualities of good leather. The quicker skins andhidcs are tanned, the more remarkably are they distinguished by these qualities. On the contrary, the longer they are kept in contact with tanningdiquorspthe more they are deprived of them. The reason is this: Water and gallic acid do not precipitate 'gelatinc, and consequently do notaet as tanning-agents. They gradually dissolve and destroy skins and hides. Yet all tanning-liquors contain both these deleterious agents in great excess. Most.

exogenous trees, as the oak, horse-chestnut, and all gall-nuts of the oak, contain gallo-tann'ic acid, that is,

a mixtureof gall'ic andtannic acids. Besides, a solution of tannic acid in w'atei-, (the real tnnningmgenh) .exposed'to the air, is decomposed, absorbing oxygen and evolving carbonieacid', andproducing a colored liquid,

anda very large quantity of'gallioacid. The harkometer, therefore, is no real test of the strength of tanningliquors; for one, poor in tannic acid and rich in gallic, (which is worthless as a. tanner and injurious to animal tissues,) may have as great a specificgravity as one rich in tannic acid-and poor in gallic. Fresh infusions of bark, immediately us'ed, are, therefore,'much stronger in tannic acid and weaker ingallic, than old liquors, long exposed to the air. It follows, therefore, most logically, that my process of quick tanning, whichnever needs to occupy over from ten to thirty days, will produce a..tougher' and more durable leatherpthan the old method, which requires'thc skins and hides to be in contact with old liquors, exposed to atmosphericchanges, from three'to six months, and sometimes a full year.

Moreover, the profits of my process constitute another recommendation of it. Tanners who now turn over their capital only twice, or, at most, threetimes a year, can do so, by the use of my invention, every month in the year. t v i v The preceding process, which I have described,is limited to the use of one revolving tanner. But, in a moreextended tan-yard, where a la'r ge business is desired to be car'riedon, my process of quick tanning is designed to he developed on a more extended scale by the use of a series pf communicating vats and co=efiicient revolving tanners. Thedrawings representthe first. three of such a series. I

I To illustrate the method of operating such a series: Suppose the most concentrated liquor employed in tanning, or finishing the tanning of skins and hides, be 30 in the finishing-vat 13. Suppose fifteen days be the period of time allotted to tan completely one batchof raw skins or hidesf Again, suppose these skins and hides require, for complete tanning, to be revolved, during one day each, in fifteen different liquors,.each increasing in strenth 2. Then a. series of fifteen vats and'tanners, construct-ed like the three shown in the drawings, would best fulfil the requirements of these hypotheses. To charge the whole series of vats vwith theirrespectiveliquors, and their revolving tanners with skins or hides, the following method may be adopted: The communication between the first and seeond'vat is first closed. The first revolving tanner is charged with raw hides. The" first vat is supplied with-liquor marking 2. This should be a fresh solution .of acid,

merely lukewarm. The tanner is thenput in motion. The revolution goes on one. day, or less. The second day the liquor is siphoned out of the first vat. The communication is opened between the first and second vet, and shut between the second and third. The hides in the first tanner are advanced into the second, and raw hides are again placed in the first. The first vatis again filled with tanning-liquor marking 2, and the second vat is charged with liquor marking 4. The two revolving tanners are now put in motion. At the same time, .a stream 'of. liquor marking 4, isfed into the second vat, and the same stream, or one equal to it, will flow through the hole in the partition between the first a nd'second vats, and also out of the overflow-orifice in the top. part of the first'vat, similar to that .shown in the vat D, at the letter T. This inflowing stream should he graduated, as nearly as possible, so as to prcserve'the liquor in the second vat as near to 4, and in the first vat as near to2 as possible. On the third day, the communication is shut between the third-and fourth vat, and the-hides in the second tanner placed in the third, and those in the first changed to the second,

and raw hides put into the first. The third vat is now filled'with tanning-liquor marking 6.; The communication is opened between the second and third vat,' Th-e feed-pipe is removed-from the second vat to the third,

and liquor marking 6 discharged through it into the. third vat. The three revolving tanners, thus charged,

are made to rotate during the third-day. The feed-pipe should deliver the tanning-liquor into the third vat,

by a flow so graduated as to preserve the liquor in that vat at 6, and in the second vatat 4, and i nthe first at 2, or as nearly so as possible. In this manner the. entire series is to be charged with liquor and hides, increasingthe strength of the acid 2 in each successive vat of. theseries, and advancing the hides forward, every day, and supplying the first tanner daily with raw'hides. On the morning of the sixteenth day, the

tanner 13,5110 in the drawings as the finishing one of the series, is ready to be opened, and the first batch of completely-tanned leather discharged. The vats are all full of tanning-liquor, that in the .first marking 2, and that in the fifteenth, as B, for example, marking 30. A feed-pipe is now connected with the finishing-vat B, at S, and supplies the whole series of vats with the tanning-liquor. It enters the vat B, marking 30, where it is lightened in specific gravity, by being robbed of its tannin by the hides in the tanner E; from thence it passes into the vat'G, through a hole bored through the partition, Q, near the bottom, marking 28; from thence, deprived of more tannin by the hides in-the tanner F, it flows into the vat D, marking 26; and so on, to the end of the series, decreasing in strength by 2 in each successive vat ofthe number, until it flows out of the raw-hide vat marking 2.

I It isnot possible-to preserve, with absolute accuracy, this exact ratio in the decreasing strength of the liquors. But an approximation to it, suflticiently near for all practical purposes, may be made by a skilful operator. It is'obvious that the inflowing stream through S, into the vatB, will be the measure of the inflowing stream from B into C, and from C into'D, and so on, through the whole series of vats. It is further evident that the outfiowing stream from the raw-hide vat, through a hole nearer its top, represented in the drawings by the letter T, will be poorer in tannic acid than the same-sized stream flowing through the pipe S, into the vat B, by the amount of acid taken up' by all the hides, in the series-of tanners, between-these two streams.

If, therefore, the several-tanners are charged with nearly the same amount of skins in hides, and rotated with the same speed,.for the samelength of time, the aggregate amount of tannin taken upwill be. distributed equally enough through the series of hides for all practical purposes.

- 76,134 i l 5 a Having .thus charged the vets and tumors, the daily routine required to keep them in constant operation,

turning out a batch of tanned skins or hides every day, is to remove the tanned leather from the tanner E, advance the hides from F to E, and friem G to F, and so on, through the sei'ies, putting raw hides eiskins into the last tanner; keep the tanners rotating and the concentrated tanning-liquor flowing through the pipe 3.

I do not intend to he understood ties-confining myself strictly, but only substantially, to the details hereinbefore set forth.

A tan-yard thus constructed and operated, can-do a. large business with but few hands.

Having described the novelties and uses of my invention, what I elaim, and desire to secure by Letters Patent, isi i The use of the revolving tanners E F G, armed with pins, and working partially submerged in tan-liquor, in the vats B G D, for the purpose of tumbling hides and skins against the said pins, and forcing out the exhausted water from their centres, and working into them fresh tannin, substantial "yin the manner and for the purposes set forth.

HENRY W. ADAMS.

Witnesses:

Amos'T, Bxsnn, Jr.-, JOHN MILLER. 

